Partially-automated or monitored driving systems are designed to assist drivers in operating a vehicle safely and efficiently on the road, for example, using techniques such as eye-tracking of the driver to send a warning when the driver becomes inattentive, lane tracking of the vehicle to send a warning to the driver when the vehicle is leaving its lane, and controlling vehicle velocity based on distance to a vehicle ahead of the driver when adaptive cruise control is activated by the driver. Fully or highly automated driving systems are designed to operate a vehicle on the road either without or with low levels of driver interaction or other external control, for example, self-driving vehicles.